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Aviation History
1988
1988 - 0089.PDF
Ariane 5: T minus seven years and counting The time: February 1995. The place: ELA 3 at Kourou. After seven years hard labour, this is the moment of truth: flight A501. The 50m-tall, 750- tonne Ariane 5 sits poised for lift off. The HM60 Vulcain cryogenic engine of the H155 core stage, based on gas cycle designs more than 30 years old, ignites and builds up to full thrust. Then, in simulta neous golden flashes, the two P230 solid rocket boosters (SRBs) ignite, committing the vehicle to its maiden flight on 1,590 tonnes of thrust. At P230 burnout, 125sec later, the SRBs are jettisoned and parachute to the Atlan tic Ocean for recovery. The HM60 continues to burn. Cut-off occurs at T+615sec. The LE5 second stage, with its test pay load in a 21 • 7m-long fairing, sepa rates and its engine ignites, burning for 800sec. At burnout the test payload is placed into a low Sun-synchronous orbit. Flight A502 will follow later in 1995, carrying three payloads to geostationary transfer orbit, before Ariane 5 is declared operational.* Three commercial missions begin in 1996, building up to nine a year in the year 2000. Meanwhile, in 1998, test flight A503 will place the manned Hermes spaceplane into a 500km orbit inclined at 28-5°. That, at least, is the plan. Although it was- given the green light at the Esa Council meeting at The Hague in November, the 2 • 5 billion accounting unit FLIGHT INTERNATIONAL, 16 January 1988 Tim Furniss profiles the new Ariane 5 launch vehicle, given the green light at the recent Esa Council at The Hague. Ariane 5 programme has still to convert many critics. It has been designed to meet the projected primary commercial market which sees the need to orbit commu nications satellites, the majority of which will by then weigh up to 2,800kg, into Geostationary transfer orbit (GTO) on dual launches in 1995. Market predictions are such that Esa confidently announces that 80 per cent of Ariane 5 missions will be in the dual-satellite configuration, coupling a 2,800kg to 3,200kg satellite with one 2,200kg to 2,800kg satellite, and 20 per cent with one 2,000kg satellite with two Pam D2-class 1,200kg to 1,600kg payloads on a triple launch. Market predictions, however, also indi cate that the number of Pam D-class satellites will decrease by 50 per cent in the ten years from 1990 to the year 2000. The market sees 24 missions to GTO in 2000, compared with 21 in 1990. There will also be an increased market for low-Earth- orbit missions, particularly to polar Sun- The Ariane 5/Hermes combination could provide Europe with a small reuseable shuttle vehicle synchronous orbits. On a typical commercial mission, Ariane 5 is to reduce the cost over a similar Ariane 4 launch by 10 per cent and to be commercially competitive. The extent to which the development costs will have underwritten the "commercial" vehicle will be seen when the launch price is announced, as Arianespace begins to market the vehicle in about 1991. The cost of the "commercial" vehicle will include those contributing towards making it man-rated. This partly explains why Ariane 5 is in danger of becoming a European "Space Shuttle" story, attempting to be all things to everybody, and in the end compro mising all of its objectives. For Ariane 5 is not just a commercial satellite launcher, but also the launch vehicle for the Hermes manned spaceplane and the freighter craft carrying elements of the Columbus space station into orbit. The requirements to carry a redesigned Hermes have already caused Ariane 5 to be uprated twice. The original specifica tion denoted solid rocket booster tonnage at 170 tonnes and the core stage with 120 tonnes. There has been an increase of 60 tonnes per SRB and 35 tonnes in the core stage in two years. No wonder some observers fear that Ariane 5's commercial viability will be jeopardise with the 21-tonne Hermes in the saddle. .7,1
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